Chromophore and polymer capable of detecting the presence of various neurotoxins and method of use

ABSTRACT

Applicants have produced a chromophore and a polymer that are highly sensitive to the presence of various agents, including organophosphates, pesticides, neurotoxins, metal ions, some explosives, and biological toxins. The detection is accomplished by detecting a change in the fluorescence characteristics of the chromophore or polymer when in the presence of the agent to be detected. The chromophore and polymer may be incorporated into sensors of various types, and they are adaptable for potential field use in areas where detection of these types of agents is desired.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 60/646,920 filed Jan. 25, 2005, which is incorporated byreference herein in its entirety.

This application is also a divisional of copending non-provisionalapplication Ser. No. 11/338,261 filed Jan. 24, 2006, which is alsoincorporated by reference herein in its entirety.

GRANT REFERENCE

This research was federally funded under Defense MicroelectronicsActivity (DMA), Department of Defense, Contract No. 1-194003-04-2-0404.The government may have certain rights in this invention.

BACKGROUND OF THE INVENTION

A wide variety of toxins exist in nature and they can also besynthetically produced. They vary in their structural complexity,ranging from formic acid produced by ants to protein toxins produced byseveral bacteria. Neurotoxins are among the most poisonous and fastestacting toxins. They specifically target the nervous system of animals,including humans, by interfering with the transmission of nervoussignals. Neurotoxins are generally more lethal than toxins produced bymicrobes, and can cause incapacitation or death of the affectedindividual within minutes of exposure. As a result, neurotoxins havebeen and will continue to be significant potential candidates forweaponization. Examples of weaponized neurotoxins include Tabun (GA),Sarin (GB), Soman (GD), Cyclosarin (GF), DFP, DMMP, and VX, amongothers.

Each of these listed neurotoxins, and others, are organophosphates.Their neurotoxic activity arises from their ability to inhibit thefunctionality of acetylcholine esterase (AChE). Under normal conditions,AChE catalyzes the hydrolysis of the neurotransmitter acetylcholine(ACh) to acetic acid and choline. This reaction allows cholinergicneurons to return to their resting state after activation. In thepresence of organophosphates, however, AChE is inhibited and neurons areunable to return to their resting state. In low doses, this results ineye watering and excessive salivation, and in higher doses, individualsare afflicted with various conditions, including salivation,lacrimation, urination, defecation, gastro intestinal upset, and emesis.When dosage is high enough, exposure to these compounds can also resultin death. It is these properties of organophosphates that make themparticularly suited for use not only as pesticides, but also aspotential chemical warfare agents.

Because of this potential use of organophosphates as weapons and thespeed with which they attack the human body after exposure, there is acritical need for an efficient method to quickly and accurately detectthese highly toxic compounds. While there have been several developmentsin the past decade for detection of organophosphates, includingcolorimetric detection methods, surface acoustic wave (SAW) devices,enzymatic assays, and interferometry, each of these has at least onedisadvantage. The limitations of these existing methods include slowresponse time, lack of specificity, low sensitivity, operationalcomplexity or non-portability. For example, two major approaches thathave received extensive attention are immuno-based assays and DNAsequencing schemes. However, immuno-based assays are difficult toimplement outside of the laboratory because of the instability of theantibodies involved and the necessity of including unstable reagents inthe assay. And DNA sequencing techniques are time andinstrument-intensive, so therefore they cannot meet the requirements forpractical field use. Additionally, both approaches require extensiveoperator training to be properly implemented.

Another common approach to sensing the presence of organophosphates isto rely upon an immobilized AChE detector coupled to a transducer suchas Ph electrodes, fiber optics, and piezo electric crystals. Thisapproach, however, is hampered by several limitations. For example,immobilized enzymes are sensitive and detect a broad spectrum of AChEinhibitors. Because of this broad range sensitivity, they lackselectivity and are prone to false positive alerts, particularly whenexposed to choline mimics.

In addition to detection of organophosphates, there is a need for anysensor to convert a detector's chemical, mechanical, or optical changeinto a measurable signal when the organophosphates are present. Manydifferent types of sensors are known in the art. For example, chemicalsensors often detect conductivity changes, amperometric changes, orpotentiometric changes. Optical sensors detect changes in emission orabsorption. Mechanical sensors can detect changes in mechanicalproperties or impedence. However, none of the known sensors are or canbe linked to a detection sensitive material which provides bothquickness of alert and accuracy of detection.

As can be seen from the foregoing, there is a need in the art fordevelopment of a way to quickly detect the presence of neurotoxins insuch a way that can be utilized in non-laboratory applications, byminimally trained personnel, with a low incidence of false positivealerts.

It is therefore an object of the present invention to provide aneurotoxin-sensitive compound that can selectively detect variousorganophosphates agents over a range of concentrations and conditions.

A further object of this invention is to provide a compound for use inoptoelectronic sensors to detect organophosphates agents.

It is another object of this invention to provide a polymer capable ofuse in optoelectric sensors for detection of organophosphates agents.

Another object of this invention is to provide a method for detectingorganophosphate agents using lumiphoric compounds.

These and other objects of the present invention will become apparentfrom the description of the invention that follows.

BRIEF SUMMARY OF THE INVENTION

The invention described herein provides a practical method for usingorganic compounds and/or polymers to detect various bioactive and othertypes of agents that include halogen or methoxy groups, includingorganophosphates, neurotoxins, pesticides, metal ions, and combinationsthereof. When the detection chromophore or polymer of the invention comein contact with the compound to be detected, the detection compoundreacts with a compound to be detected, thereby changing the fluorescenceproperties of the detection compound. This change in fluorescence canthen be measured and indicates the presence of the compound to bedetected. The chromophore or polymer may be used in a variety ofsensors, including optical electronic sensors, biosensors, and surfaceacoustic wave sensors for detection of the various organophosphate andother compounds that may be detected.

Transition metal complexes that are luminescent in room-temperaturesolution have been used in a variety of chemical and biochemicalapplications. Many of these applications require that the metallumiphore be functionalized so that it can be appended to a molecule ormacromolecule of interest or activated by chemical reaction. Suchfunctionalized lumiphores have been used in electron-transfer studies,in the design of new biosensors, and in the formulation of emissivepaints.

In the present invention, the binding capability of pyrazines andaminopyrazines to bind metals and other organic and biomolecules isutilized to synthesize new organic or polymeric materials whosefluorescence properties change when coming into contact with appropriateanalytes.

This change in fluorescence characteristics can be used to produce asensor to assist in the detection of these various compounds. Thesemulti valiant interactions produce a distance-dependent fluorescenceenergy transfer, and can be used in a regent-free, highly sensitive, andspecific sensing technology for detection of these toxins.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the emission spectra of the chromophore of thepresent invention with dimethylchlorophosphonate (DMCP).

FIG. 2 illustrates the UV-Vis absorption and emission spectra ofpolyparaphenylene derivatives having amino pyrazine units as describedin Example 1.

FIG. 3 illustrates the intensity of fluorescence of polymer andpolymer+dimethylchlorophosphonate (DMCP).

FIG. 4 illustrates the intensity of fluorescence of polymer andpolymer+dimethyl methylphosphonate (DMMP).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In its broadest sense, the invention comprises the use of a polymer orchromophore with luminescent properties that are either enabled (in thecase of the chromophore) or disabled (in the case of the polymer) in thepresence of a compound to be detected, and methods of using said polymerand/or chromophore to detect such compounds. In addition, the inventionincludes a method of producing the polymer and chromophore.

In a preferred embodiment, a polymer is produced that ceases tofluoresce when contacted with an organophosphate, neurotoxin, pesticide,metal ion, biological agent (or combinations thereof) or other types ofcompounds containing at least one halogenated group. Specific examplesof halogenated neurotoxins include sarin, soman, GF, and DFP. While thepresent invention specifically refers to the use of detection agents foruse in detecting neurotoxins, it is to be understood that the presentinvention is useful for detection of numerous compounds that contain oneor more of the functional groups of interest.

In contrast to the polymer, the chromophore of the present inventionfluoresces when contacted with an organophosphate, neurotoxin,pesticide, metal ion, biological and/or other types of compoundscontaining either a halogenated or methoxy-functional group.

The respective modes of detection of the polymer and the chromophoreallow an effective dual means of detecting and identifying variouscompounds containing a halogenated and/or methoxy group. For instance,the chromophore can be used to generally detect the presence of aneurotoxin. Once a neurotoxin is detected, the polymer can be used tomore specifically identify whether the neurotoxin is one containing ahalogenated group. Alternatively, the polymer and chromophore can alsobe used individually to detect the presence of various halogenatedand/or methoxylated neurotoxins.

The backbone of the polymer is generally made up of some combination ofat least one of aminopyrazines, pyrazine, aminopyridine, or any aminecontaining an aromatic moiety; one or more of thiophene, pyridine,bipyridine, quinoline, isoquinoline, paraphenylene, hydroxylparaphenylene, a phenyl group, or any hetero aromatic system. Thebackbone has a total number of between 1 and 100 units, with about 5-20being preferred. The backbone preferably consists of pyrazine,aminopyridine, or aminopyrazine, with aminopyrazine being mostpreferred.

Preferred polymers of the present invention have the following generalformula:

wherein R₁ is H, alkyl, cycloalkyl, benzyl, or any aromatic,heteroaromatic, or heterocyclic group; and n is an integer between 1 and100; and R₂ is a C₆-C₁₅ alkyl chain. Again, n is preferably 5-20.

Most preferred polymers of this invention have the following generalformula:

wherein R₁ is H, alkyl, cycloalkyl, benzyl, or any aromatic,heteroaromatic, or heterocyclic group; and n is an integer between 1 and100, with 5-20 being preferred.

The chromophore of the present invention has the following generalformula:

wherein R is H, NH₂, an aliphatic chain, or an aromatic group. Thealiphatic chain is preferably C₁-C₈.

Preferred chromophores of the invention have one of the followingformulas shown below:

The chromophore and polymer are generally prepared by Suzuki couplingreactions. Such reactions are well known and understood in the art. Ingeneral, an organoborane is reacted with an organic halide in an organicsolvent, such as tetrahydrofuran (THF) and ethers. This reactionpreferably occurs in a nitrogen atmosphere with vigorous stirring at atemperature between 90-110° C. However, other temperatures, atmospheres,and reaction conditions are also appropriate, as would be understood topersons skilled in the art. The use of a palladium catalyst is alsopreferred. Once the reaction is complete, the organic phase is separatedand the polymer precipitated therefrom. The precipitated polymer is thenseparated and dried using conventional means or can be retained insolution.

In the absence of neurotoxins, the polymer fluoresces in the presence ofultraviolet light. However, upon contact with the halogenated phosphateesters of neurotoxins, the polymer quenches the fluorescence of theneurotoxin, thereby facilitating its detection. This fluorescencequenching is the result of the NH₂ group of the conducting polymerhydrolyzing the halogenated phosphate ester and releasing acid which inturn oxidizes the polymer.

The detection of the organophosphate molecule by the change influorescence characteristics of the polymer occurs quite rapidly,typically in less than three seconds. Given this fast response time, thepolymer is particularly suited for use in optoelectronic sensors. Inaddition to the above-described polymer, a non-polymeric chromophore mayalso be used to detect the presence of the organophosphates and otherbiological agents already described above. The chromophore has thereverse fluorescence characteristics as the polymer, meaning that in theabsence of organophosphate molecules, the chromophore does not fluorescein the presence of ultraviolet light. The chromophore gains itsfluorescence under ultraviolet light when a neurotoxin containing eithera methoxy or halogenated group is present. The fluorescence is theresult of the reaction of the OH of the chromophore with thesefunctional groups.

The chromophore and polymer have different mechanisms of action todetect the presence of organophosphates or other compounds. Generally,the polymer hydrolyzes the halogenated phosphate ester of theorganophosphate molecule and releases acid, which in turn oxidizes thepolymer. This leads to formation of imine form of the polymer, which isnot fluorescent after binding with the organophosphate. This imine formis depicted below:

Cyclic voltammetry shows that the polymer is oxidized in two steps, andthe EIS measurement shows an increase in resistivity with oxidation. Itis the increase in resistivity that explains the quenching of thefluorescence in response to the presence of organophosphate or othermolecules capable of detection. FIG. 3 illustrates the intensity offluorescence of unbound polymer compared to polymer bound to DMCP. FIG.4 illustrates that polymer bound to dimethylmethylchlorophosphonate (anon-halogenated neurotoxin) has the same intensity of fluorescence asunbound polymer.

As noted, the chromophore detects the presence of organophosphates orother detectable molecules by interaction between the hydroxyl group andthe methoxy or halogenated group of the neurotoxin molecule. This leadsto a cyclization reaction which in turn produces the fluorescentmolecule depicted below. The overall reaction is also shown:

where A⁻ is PO₂(OCH₃)₂ ⁻. FIG. 1 is a graph showing the emission spectraof the most preferred chromophore of the present invention (as shownabove) with dimethylchlorophosphonate (DMCP).

Based on the above-described mechanisms of action, the chromophore andpolymer described are able to detect a wide variety of compounds. Thechromophore can detect any neurotoxin having a methoxy or halogenatedgroup, and the polymer will detect halogenated neurotoxins specifically.Detectable compounds include organophosphates having the requisitehalogen or methoxy group, such as sarin, cyclosarin, soman, tabun,diisopropylfluorophosphate, diethylchlorophosphate, VE, VG, VM, VX,metrifionate, pyridostigmine, and physostigmine; explosives such asplastic explosive or trinitrotoluene; and metal ions, such as iron,cobalt, nickel, copper, a transition metal ion, or a main group metalion.

For years military force have used detection devices to identify thesesame materials but even today's best detection measures may requireminutes for the user to receive an accurate alert to a potential hazard.Some detectors are quicker but they also provide more false alerts.

The polymer and chromophore of the present invention can accuratelyidentify trace amounts of poisons or explosives having halogen and/ormethoxy functional groups in seconds. These detection molecules candetect leaks in shipping containers of certain industrial chemicals,detect certain explosive compounds and detect an entire family ofneurotoxins. In addition to giving advanced notice to the presence ofhazards, the detection molecules can be used to authenticate theelimination of chemical agents or toxic substances during aninvestigation or clean-up operation.

The polymers of the present invention notify users via multiple feedbackmethods. They can be set to fluoresce in ultraviolet light yet remainclear in visible light. When in this mode, the fluorescence will quenchas a toxic substance or explosive compound comes into contact it.Alternatively, the chromophore can provide no initial ultravioletfluorescence, but fluoresces upon exposure to a toxic substance orexplosive compounds.

The detection molecules of this invention also have the unique propertyof providing enough electrical activity upon coming into contact with ahazardous substance so that it can be integrated into many of today'sexisting electrical sensors.

Rapid alert notification to the presence of a fast acting neurotoxin isextremely important. Many chemical agents cause injury or death in lessthan a minute. Speed is also essential when multiple yet rapid andeconomical detections must be made (for example, hand screening ofluggage). The detection molecules of the present invention provideaccurate detection within 2 to 3 seconds of contact with a targetsubstance as compared to minutes with similar technologies. These uniquemolecules are designed to detect trace amounts of:

-   -   the entire family of halogenated chemical compounds with very        high selectivity;    -   the chemical warfare agents VX, GF, GB (Sarin), GD, (Soman) and        GA (Tabun);    -   explosives (various plastic explosives and TNT); and    -   pesticides (organo-phosphonates like DFP and DMMP).

The detection molecules need only be applied in strengths ranging fromparts-per-millions to part-per-billions. Further, under certaincircumstances, the molecules can be reconditioned for repetitive use.

The detection molecules of the instant invention can be appliedseparately or together, and as an individual coating or mixed with othercoatings. They can be sprayed or painted on to a surface, and can beapplied to such simple materials a tape or cloth swabs, or applied tomuch more complex devices such as electronic sensors or electronicnoses. Sensors incorporating either or both of the chromophore and/orpolymer can be easily used in any location in which fast detection ofneurotoxins is desired. Examples might include potential targets forterrorist attacks, such as subways, airports, aircraft, or governmentbuildings. The basic performance and functionality of these molecules indetecting neurotoxins have been verified with fluorescence measurements,impedance testing and cyclic voltammetry.

In addition to being used to detect neurotoxins in the context ofterrorism or chemical warfare, the polymer and chromophore described canalso be used to detect the presence of organophosphates in the contextof medical diagnosis or treatment monitoring. In fact, the polymer andchromophore may be used to detect neurotoxins in virtually any desiredapplication.

The following examples are offered to illustrate but not limit theinvention. Thus, they are presented with the understanding that variousformulation modifications as well as method of delivery modificationsmay be made and still be within the spirit of the invention.

Example 1 Preparation and Properties of a Preferred Polymer

A preferred polymer of the present invention was prepared by thefollowing method:

a) 2,5-Dibromo-4-dodecyloxy phenol

2,5-Dibromohydroquinone 3 (40.2 g, 0.15 mol) was dissolved in a solutionof sodium hydroxide (9.2 g, 0.23 mol) in 1.5 L of absolute ethanol atroom temperature under nitrogen atmosphere. The reaction mixture waswarmed to 50-60° C. with constant stirring. The dodecylbromide (36 ml,0.15 mol) was added drop wise to the above reaction mixture at 60° C.After 10 h of stirring under nitrogen atmosphere, the reaction mixturewas cooled and the precipitate formed was filtered and washed withmethanol. This precipitate was identified asdialleylated-2,5-dibromohydroquinone as a side product. The filtrate wasevaporated to remove the solvent. 2 L of distilled water was added tothe residue and the mixture was acidified with 36% HCl, boiled gentlyfor 1 h and cooled. The resulting precipitate was collected byfiltration, washed with water and dried in vacuo. The crude product waspurified by column chromatography using a mixture of solvents(CH₂Cl₂:hexanes, 4:6) to get the pure product in 60% yield.

¹H NMR, (CDCl₃, δ ppm): 7.25 (s, 1H), 6.97 (s, 1H), 5.16 (s, 1H), 3.92(t, 2H), 1.62 (q, 2H), 1.4 (m, 18H); 0.88 (t, 3H). ¹H NMR (CDCl₃, δppm): 7.25 (s, 1H), 6.97 (s, 1H), 3.92 (t, 2H), 1.80 (q, 2H), 1.4 (m,18H); 0.87 (t, 3H). ¹³C NMR (CDCl₃, δ ppm): 149.95, 146.64, 120.16,116.49, 112.34, 108.26, 70.25, 31.81, 29.55, 29.47, 29.26, 29.20, 28.97,25.82, 22.60, 14.04.

b) 2,5-Dibromo-1-benzylozy-4-dodecyloxy benzene

Benzyl bromide (3.8 ml, 0.031 mol) was added drop wise to a stirredsolution of 2,5-dibromo-4-dodecyloxy phenol (a) (6.95 g, 0.015 mol) andanhydrous K₂C0₃ (3.28 g, 0.023 mol) in 700 ml of absolute ethanol at40-50° C. The reaction mixture was stirred for 10 h at 50° C., progressof the reaction was monitored using TLC, cooled to RT and evaporated toremove the solvent. An equal volume of distilled water was added to theresidue and the mixture was stirred for one hour at 0° C. The resultingprecipitate was collected by filtration, washed with water, and dried invacuum. Recrystallization was done in methanol to get 80% yield.

¹H NMR (CDCl₃, δ ppm): 7.46 (m, 5H), 7.21 (s, 1H), 7.15 (s, 1H), 5.11(s, 2H), 3.99 (t, 2H), 1.85 (q, 2H), 1.32 (m, 18H), 0.95 (t, 3H). ¹³CNMR (CDCl₃, δ ppm): 150.51, 149.49, 136.16, 128.50, 128.10, 127.17,119.32, 118.31, 111.53, 111.01, 71.99, 70.19, 31.83, 29.56, 25.84,22.60, 14.02

c) 1-Benzyloxy-4-dodecylozyphenyl-2,5-bisboronic acid

1.6 M Solution of butyl lithium in hexanes (55 ml, 0.088 mol) was addedslowly to a solution of dibromide b (11.57 g, 0.022 mol) in a mixture ofsolvents diethyl ether (150 ml) and THF (150 ml) under nitrogenatmosphere at −78° C. The solution was warmed to RT and cooled again to−78° C. Triisopropyl borate (51 ml) was added drop wise within 2 h.After complete addition, the mixture was warmed to RT and stirredovernight. Water was added and the mixture stirred for 24 h. Thecrystalline mass was recovered by filtration. The product was recrystallized from acetone in 80% yield.

¹H NMR (DMSO-d₆, δ ppm): 7.80 (s, 2H), 7.75 (s, 2H), 7.46 (m, 5H), 7.29(s, 1H), 7.17 (s, 1H), 5.11 (s, 2H), 3.99 (t, 2H), 1.73 (q, 2H), 1.24(m, 18H), 0.85 (t, J=6 Hz, 3H). ¹³C NMR (DMSO-d₆, δ PPM): 157.00,156.22, 137.16, 128.38, 127.77, 127.52, 118.28, 117.70, 70.05, 68.30,31.2, 28.89, 25.38, 22.00, 13.87.

d) 1-Benzyloxy-4-dodecyloxy phenyl-2,5-bis(trimethylene boronate)

Diboronic acid c (8.2 g, 0.018 mol) and trimethylene glycol (5.2 in],0.072 mol) were added to toluene (150 ml) at RT. Then the reactionmixture was refluxed for 3 h. The solvent was removed by rotovap. Theresidue was dissolved in CHCl₃, dried over sodium sulfate and filtered.The solution was evaporated and the residue was re crystallized fromhexanes. The recrystallized product was used without furtherpurification for polymerization.

¹H NMR (CDCl₃, δ ppm): 7.35 (m, 5H), 5.05 (s, 2H), 4.16 (d, 8H), 3.85(t, 3H), 2.02 (m, 4H), 1.57 (m, 2H), 1.27 (m, 18H), 0.88 (t, 3H). ¹³CNMR (CDCl₃, δ ppm): 157.73, 156.92, 138.28, 128.06, 127.00, 120.42,119.79, 71.70, 69.70, 61.91, 31.81, 29.55, 27.22, 25.98, 22.57, 14.01.

e) 2-Amino-3,5-dibromopyrazine

Under absence of light and at 0° C., N-bromosuccinimide (15.68 g, 88.1mmol) was added to a solution of 2-aminopyrazine (4.19 g, 44.06 mmol) indry dichloromethane (250 ml). The mixture was stirred for 20 h at 4° C.and then washed with four 40 ml portions of a saturated sodium carbonatesolution in water. The organic layer was dried (MgSO₄) and evaporatedunder reduced pressure, affording the title compound as 12.8 g of alight brown solid. Column chromatography, using silica and adichloromethane/ethyl acetate (3/1) mixture as the eluent, yielded pure2-amino-3,5-dibromopyrazine as 5.00 g (65%) of a light yellow solid.

¹H-NMR (CDCl₃, 400 Mhz): 8.09 (s, 1H), 4.95 (211, NH) ppm. ¹³C-NMR(CDCl₃): 153.5 (C-2), 144.3, 131.9, 126.8 ppm

f) Synthesis of Poly(P-Phenylene)-Co-Amino Pyrazine Polymer

Diboronic ester d (0.97 g, 0.186 mmol) and dibromo aminopyrazine e(0.458, 0.186 mmol) were added to dry THF (10 ml) under nitrogenatmosphere. 2M Na₂CO₃ (15 ml) was added to this followed by palladiumcatalyst tetrakis(triphenylphosphino)palladium (1.5 mol % with respectto monomer d). The mixture was then heated to 100° C. for 72 h in aflask with vigorous stirring. After the reaction, the organic phase wasseparated and the polymer precipitated from hexane. The precipitatedpolymer was separated and dried to yield 0.5 g of polymer (Yield=60%).GPC analysis showed a number average molecular weight of 5300.

This leads to production of the following preferred polymer:

Example 2 Preparation of a Preferred Chromophore

a) Benzyl bromide (7 ml, 0.05 mol) was added drop wise to a stirredsolution 2 bromo phenethyl alcohol (10 g, 0.0496 mol) and anhydrous NaH(2.28 g, 0.05 mol) in 100 ml of dry THF at 40-50° C. The reactionmixture was stirred for 10 h at 50° C., progress of the reaction wasmonitored using TLC, cooled to RT and evaporated to remove the solvent.An equal volume of distilled water was added to the residue and themixture was stirred for one hour at ambient. The organic layer wasseparated, dried and evaporated. To the resulting liquid 100 ml of 5%ethanolic solution of NaOH was added and refluxed for 3 hr. Theresulting solution was evaporated and extracted with ether to give thebenzyl protected phenethyl alcohol as a clear liquid at 80% yield.

¹H-NMR (CDCl₃, 400 Mhz): 7.5 (d, 1H), 7.3 (m, 7H), 7.08 (d, 1H), 4.53(s, 2H), 3.7 (t, 2H), 3.07 (t, 2H) ppm. ¹³C-NMR (CDCl₃, 100 Mhz):138.43, 132.96, 131.37, 129.01, 128.58, 128.20, 127.78, 127.76, 127.57,124.87, 73.12, 69.56, 36.71 ppm.

b) 1.6 M Solution of butyl lithium in hexanes (66 ml, 0.1 mol) was addedslowly to a solution of 2-bromo O-benzyl phenethyl alcohol (9.7 g, 0.033mol) in a mixture of solvents diethyl ether (150 nil) and THF (150 ml)under nitrogen atmosphere at −78° C. The solution was warmed to RT andrecooled to −78° C. Triisopropylborate (23.1 ml) was added drop wisewithin 2 h. After complete addition, the mixture was warmed to RT andstirred overnight. Water was added and the mixture stirred for 24 h. Theorganic phase was separated and column chromatography of the resultingviscous liquid using dichloromethane as the eluent gave the boronic acidas white crystalline solid in 65% yield.

¹H-NMR (CDCl₃, 400 Mhz): 7.8 (d, 1H), 7.4 (t, 2H), 7.3 (m, 4H), 7.2 (d,1H), 7.1 (d, 1H) 4.53 (s, 2H), 3.75 (t, 2H), 3.07 (t, 2H) ppm. ¹³C-NMR(CDCl₃, 100 Mhz): 143.78, 136.79, 134.15, 130.44, 129.32, 128.69,128.20, 127.95, 126.13, 73.74, 72.47, 36.89 ppm.

c) Under absence of light and at 0° C., N-bromosuccinimide (7.84 g,44.05 mmol) was added to a solution of 2-aminopyrazine (4.19 g, 44.06mmol) in dry dichloromethane (250 ml). The mixture was stirred for 20 hat 4° C. and then washed with four 40 ml portions of a saturated sodiumcarbonate solution in water. The organic layer was dried (MgSO₄) andevaporated under reduced pressure, affording the title compound as 5.90g of a light brown solid. Column chromatography, using silica and adichloromethane/ethyl acetate (3/1) mixture as the eluent, yielded pure2-bromo-5-aminopyrazine as 5.00 g (65%) of a light yellow solid.

¹H-NMR (CDCl₃, 400 Mhz): 8.09 (s, 1H, H-6), 7.77 (s, 1H, H-3), 4.65 (bs,2H, NH) ppm. ¹³C-NMR (CDCl₃, 100 Mhz): 153.5 (C-2), 144.3 (C-6), 131.9(C-3), 126.8 (C-5) ppm.

d) The boronic acid (0.8 g, 3.26 mmol) and bromo pyrazine (0.56 g, 3.26mmol) were added to dry toluene (20 ml) under nitrogen atmosphere. 2MNa₂CO₃ (15 ml) was added to this followed by palladium catalyst tetrakis(triphenylphosphino) palladium (1.5 mol % with respect to boronic acid).The mixture was then heated to 80° C. for 48 h with vigorous stirring.The reaction mixture was evaporated, washed with water and the organicphase was separated. Column chromatography of the compound using 1:1Ethyl Acetate/Hexane mixture gave 60% of the required product.

¹H-NMR (CDCl₃, 400 Mhz): 8.15 (s, 1H), 8.01 (s, 1H), 7.25 (m, 9H), 4.58(s, 2H, —NH), 4.6 (s, 2H), 3.6 (t, 2H), 3.01 (t, 2H) ppm. ¹³C-NMR(CDCl₃, 100 Mhz): 152.95, 145.20, 141.98, 138.65, 137.71, 137.33,131.28, 130.85, 130.10, 128.56, 127.80, 127.71, 126.73, 72.97, 71.20,33.64.

e) The O-benzyl protected compound was dissolved in a mixture of dry THF(50 ml) and absolute ethanol (50 ml) at RT. 10% Pd/C (3 g) was added tothe above solution. The mixture was flushed with nitrogen gas threetimes. Two to three drops of conc. HCl was added to enhance thedebenzylation. The reaction was carried out at RT under positivepressure of hydrogen for 24 h with constant stirring. The reactionmixture was filtered through celite powder and the precipitate waswashed with absolute ethanol. The filtrate was evaporated and dried invacuum to yield the desired Chromophore at 50% yield.

IH-NMR (CDCl₃, 400 Mhz): 8.19 (s, 1H), 8.06 (s, 1H), 7.30 (m, 4H), 4.78(s, 2H, —NH), 3.6 (t, 2H), 3.05 (t, 2H) ppm. ¹³C-NMR (CDCl₃, 100 Mhz):153.08, 145.20, 141.98, 138.65, 137.71, 131.28, 130.85, 128.56, 126.73,64.26, 33.64.

This yields the preferred chromophore below:

Having described the invention with reference to particularcompositions, theories of effectiveness, and the like, it will beapparent to those of skill in the art that it is not intended that theinvention be limited by such illustrative embodiments or mechanisms, andthat modifications can be made without departing from the scope orspirit of the invention, as defined by the appended claims. It isintended that all such obvious modifications and variations be includedwithin the scope of the present invention as defined in the appendedclaims. The claims are meant to cover the claimed components and stepsin any sequence which is effective to meet the objectives thereintended, unless the context specifically indicates to the contrary.

1. A method of detecting a harmful compound comprising: contacting a chromophore comprising the following structure:

wherein R is H, NH₂, an aliphatic chain, or an amino group, with a substance suspected of containing a compound having a substituent selected from the group consisting of halogenated chemical compounds, a chemical warfare agent selected from the group consisting of VX, GF, GB (Sarin), GD (Soman), and GA (Tabun), explosives, and organo-phosphonate pesticides; allowing the chromophore to contact the substance for a time period sufficient for the polymer to bind a compound that may be present; and monitoring the chromophore to determine whether there is a change in the fluorescence characteristics of the chromophore.
 2. The method of claim 1 wherein the compound is an organophosphate selected from the group consisting of cyclosarin, diisopropylfluorophosphate, diethylchlorophosphate, VE, VG, VM, metrifionate, pyridostigmine, and physostigmine.
 3. The method of claim 1 wherein the compound is a plastic explosive or trinitrotoluene.
 4. The method of claim 1 wherein the compound comprises a metal ion selected from the group consisting of iron, cobalt, nickel, copper, a transition metal ion, and a main group metal ion.
 5. The method of claim 1 wherein the chromophore is monitored by noting the presence of fluorescence of the chromophore under ultraviolet light.
 6. The method of claim 1 wherein the compound is monitored by noting a change in the electrical activity of the chromophore.
 7. The method of claim 1 wherein a compound having a substituent selected from the group consisting of methoxy, halogen, or both is detected in a time period of less than five seconds.
 8. A method of detecting a harmful compound comprising: contacting a composition comprising a polymer comprising: a structure selected from the group consisting of (a) -(--PZ-PPP--)_(n)--, (b) -(--PZ-Ar--)_(n)--, and (c) -(--PZ-PPP-Ph--)_(n)--, wherein PZ is amino pyrazine, pyrazine, amino pyridine, or any amine-containing aromatic moiety; PPP is poly paraphenylene; Ar is thiophene, pyridine, bipyridine, or any heteroaromatic system; Ph is phenyl or an Ar group; and n is an integer between 1 and 100, and a chromophore comprising the following structure:

wherein R is H, NH₂, an aliphatic chain, or an amino group, with a substance suspected of containing a compound having a substituent selected from the group consisting of halogenated chemical compounds, a chemical warfare agent selected from the group consisting of VX, GF, GB (Sarin), GD (Soman), and GA (Tabun), explosives, and organo-phosphonate pesticides; allowing the composition to contact the substance for a time period sufficient for at least one of the polymer or the chromophore to bind a compound that may be present; and monitoring the composition to determine whether there is a change in the fluorescence characteristics of the chromophore. 